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🧪 Chemistry  ·  Solid State  ·  NEET & JEE

Which of the following correctly describes a Frenkel defect?

Answer: Does not change density of the crystal.

  • A Reduces density of the crystal
  • B Does not change density of the crystal
  • C Increases density of the crystal
  • D Produces free electrons in the crystal

Correct answer: B. Does not change density of the crystal

Explanation: In a Frenkel defect, an ion moves from a lattice site to an interstitial site; no particles are removed, so density is unchanged.

Cubic Unit Cells: Atom PositionsSimple CubicCN=6, 52.4% packedBody-Centred (BCC)CN=8, 68% packedFace-Centred (FCC)CN=12, 74% packed (densest)Corner atoms (shared by 8 cells) shown lighter; body/face-centre atoms shown solid

The three cubic unit cells: Simple Cubic has atoms only at corners; Body-Centred adds one atom at the centre; Face-Centred adds one atom at the centre of each of the 6 faces, giving the highest packing efficiency.

Concept context

Explore the ordered world of crystalline solids: unit cells, packing, defects, and how structure determines electrical and magnetic properties.

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